There is nothing worse than going out into your garage, barn, or workshop and catching the scent of mouse urine, or seeing a mouse scurrying to a hiding spot when you turn the lights on. Worse yet is what you don’t see. They could be in the walls of the shop chewing on wires or tunneling paths through foam insulation.
Once a few mice start finding their way into your workshop and take up residence they will do a lot of damage and be hard to get rid of. The best way to keep mice out of your workshop is take as many preventative measures as possible to keep them from ever getting in. I’ll share with you all the things I do to keep them out of my pole barn workshop plus a few more that I’ve researched. I’ll also give some tips on getting rid of them once they do get in.
What Damage Do Mice Cause?
As small as they are mice can cause major damage to a home or building on your property. They can even cause damage to your vehicles, boats, RVs and any other items or equipment you might have. I lost my favorite pickup truck to an engine fire caused by mice chewing on the rubber gas line and electrical wires. Here’s a list of some of the most destructive things mice do:
- Chew on electrical wires possibly causing faults or even starting fires
- Spreading disease through their droppings
- Causing dangerous ammonia levels and toxic fumes from their urine and droppings
- Stockpiling food that attracts other pests
- Creating hollow areas in wall or ceiling insulation that makes it less efficient
- Creating holes in wallboard allowing for passage into other areas
- Chewing on other items in the home or shop
Prevention
While it may be impossible to make your building 100% mouse proof, we can take steps to greatly minimize the chances of mice gaining access. We want to minimize how close they get to your shop, and if they do get close make sure they can’t get in or are repelled in other ways.
Make Them Uncomfortable Approaching the Shop
Let’s start with area outside and surrounding your shop building. Keep any junk piles, stacks of firewood, or low growing brush far away from your building. Also keeping any areas of meadow or weeds from growing too close to the barn will deter mice from approaching. Mice have many enemies and they know it. Crossing large expanses of openness is very risky for them and they will avoid doing it unless desperate.
Even temporary cover will make them bold enough to come explore the perimeter of your shop. A fresh layer of fallen leaves or couple inches of light fluffy snow will be enough to make them feel safe.
Close Off Access and Seal Up the Barn
Mice can squeeze their bodies through some incredibly small holes. One YouTuber that I frequently watch, Matthias Wandel, did an experiment to see how small a hole a mouse could fit into. From that experiment he determined that a mouse could fit through a 11/16″ diameter hole. That’s smaller than a dime! You can watch that video here.
Armed with that knowledge of how small an opening a mouse needs we can now inspect the perimeter of our buildings to look for suspect places of access and seal up the barn or garage.
Overhead Garage Doors
If your shop has a block or concrete wall foundation with a man door and overhead garage door it may seem pretty secure. From experience though, I know that mice will chew a hole in the bottom of the garage door weather stop trim along the doorjamb. That trim piece is typically made of plastic or wood and rubber. This area should be checked periodically for evidence of attempted entry.
Walk-in Man Doors
An area that is overlooked is under the brickmold of the walk-in man door. When the man door is installed there is a gap between the doorjamb and the rough framing. After several years, factory brickmold could become soft at the bottom and easily chewed through by mice. That could lead them right into the shop.
Vinyl Corner Trim
The vinyl siding corner trim on a building is another access point that isn’t always obvious. This piece of trim is like a conduit for mice to get from the ground to up to the soffit depending on the details of how your building was framed and finished. This could allow free access for mice, red squirrels or chipmunks free access to your attic space. Kritter Caps makes a product that snaps into that opening to seal it off.
There is also a copper mesh material that you can stuff into those or similar openings that keep pests out. This stuff is effective because of the metallic taste it leaves in their mouth if they try to chew through it and they just generally don’t like the feel of it.
Another great product is Mouse Shield from DAP. This is an expanding foam sealant similar to Great Stuff but it also contains an EPA registered pesticide to keep mice from chewing at it. It is also effective against bugs, birds, squirrels, and bats. You can find more information on all these pest control products on my resource page.
Wood Siding
A workshop building clad in wood siding has many opportunities for mice or other critters to find their way in. Any siding that has some texture to it will allow mice to climb up the entire wall. If this describes your siding material than you’ll need to do a thorough inspection of the entire exterior of the building from top to bottom looking for any places where there’s a gap or hole.
Even a small hole or a place where the wood is starting to decay will be an invitation for mice to start gnawing at the siding to make the hole big enough for entry. If mice smell something edible or feel warmth coming out of a small hole they will make it their mission to enlarge the hole to get into the building to check it out.
Steel Siding
Steel siding for pole barns is too smooth for mice to climb, but it does present other opportunities for mice and bugs to enter your shop. The profile of the siding has ribs or ridges that are plenty big enough for a mouse to crawl through if not sealed up. This ridges are sometimes left exposed at the bottom of the siding where it’s attached to the pressure-treated toe board.
These openings are like a welcome mat for mice. They are right at ground level and if there is any cover at all mice will have a heyday going in and out of your barn. Once mice get inside the walls of a pole barn they can run along the horizontal purlins to get everywhere in your barn.
There is an easy way to seal the bottom of pole barn steel siding with a steel trim piece called bottom trim or sometimes referred to as “rat-guard”. This rat-guard is a folded piece of sheet metal that comes in different lengths and has a lip that tucks up under the bottom edge of the siding for attachment. The profile has a lip that covers up the bottom exposed openings in the steel siding to keep pests out.
Sliding Pole Barn Doors
Sliding barn doors are the Achilles heel of critter infestation prevention. If you have a sliding door on your barn there is almost no way to seal it enough to keep mice out. There are a few things you could do to slow them down a bit and keep other bigger critters out.
Adjust the door so it has the absolute minimal clearance to the floor without rubbing. There are long lengths of brush weather seal that could be attached to the bottom of the door and along the inside of the door opening.
The last step is to install latches on the inside of the door. These latches are made specifically for sliding barn doors and have a cam action that pulls the door up tight to exterior of the barn. These are adjustable to ensure the door is tight to the barn siding.
Taking these precautions with a sliding barn door will definitely help keep the weather and drafts out, but a determined mouse will still likely find his way in. The best solution here is to replace a sliding door with an overhead door.
Pest Deterrents
Even though we’ve made every effort to seal up the workshop and keep the area around the building free of hiding places for mice, they will still attempt to gain access. There are some ways to repel mice if they do come around looking for a place to get into your shop. These deterrents use odor, noise or sight to scare the critters or repel them because it makes them sick or uncomfortable.
Scarecrows and Decoys
In my experience, using decoys such as plastic owls or rubber snakes does not really deter mice from coming around your building. I bought a plastic owl to keep birds from roosting in my barn before it was fully enclosed and it did not work at all for that. There was also evidence of mice in the building during that same period.
My theory as to why plastic owl decoys don’t work very well is that mice don’t have very good eyesight. Mice are good at picking up motion but a motionless plastic decoy that could be 10 or 20 feet away will go completely unnoticed.
Ultrasonic Noise
Ultrasonic pest repellers are electronic devices that produce ultrasonic noise that mice and other pests are supposed to be able to hear and is bothersome to them. Although I have no personal experience with ultrasonic pest repellers, I have always been skeptical about their effectiveness.
My skepticism has been reinforced by a YouTube video that I watched by metaspencer where he did a test with several different models of these devices while baiting mice in front of a game camera. Even with several ultrasonic noise makers right next to the bait, a mouse still came to eat the bait. He also tests the decibel output of four different models. Here’s a link to that video on YouTube.
Odor Repellents
There is a plethora of claims that certain odors will repel mice. Most of these are natural sources of smells that are supposedly unpleasant or irritable to rodents. There is also plenty of skepticism about all these such claims. Below is a table of all such rodent odor repellents I could find. I had planned to try most of these out myself but then I found Shawn Woods’ YouTube channel and he has videos on nearly all of repellents where he sets up tests and films them. Based on what I’ve seen on his channel there is no need for me to test any of these out myself.
| Mouse Deterrent Effectiveness | ||
|---|---|---|
| Effective | Limited | Skeptical |
| Peppermint Oil | Tea Tree Oil | Cloves |
| Eucalyptus Oil | Pet Hair | |
| Black Pepper | Human Hair | |
| Cayenne Pepper | Rubbing Alcohol | |
| Commercial Repellents | Dryer Sheets | |
| Irish Spring Soap |
Effective
From Shawn’s test I am convinced that peppermint oil will repel mice. He tested the Victor Scent-away repeller drops. He actually filmed mice that refused to enter the bait box because there where two of these droppers inside. There are many other claims that using peppermint essential oil on cloth or cotton balls will work just as effectively.
The drawback to using this as a repellent is that the oils will dry up and become ineffective over a short period of time, usually a month or two. That means you will be constantly replenishing the repellent. Possibly an effective use might be to place some of these oil scents near the doors of your shop as the weather begins to turn cold at the end of fall. That is when mice are most actively looking to find access to the indoors.
Limited
From all the research I’ve done, I’ve seen some limited success with using other essential oils, ground black pepper or cayenne pepper, and commercial repellents that usually contain peppermint oils or extracts.
I feel that these are very limited because their effective period is very short and to rely on one of these methods means eventually you will still have a mice problem. The commercial peppermint sprays seem to not be concentrated enough to provide the same repellent level as pure peppermint oil.
My recommendation is to concentrate efforts on sealing up the workshop to keep them from getting in first. Then if you find evidence of them still trying to gain access use peppermint oil around that area.
Skeptical or Debunked
For many number of reasons these odor sources such as pet or human hair, Irish Spring soap, dryer sheets, cloves, or rubbing alcohol just don’t work. While it may be true that mice and other critters don’t care for the smell of this stuff, if they are cold or hungry it will not deter them from finding what they are after.
Extermination
I don’t know if there is a building ever built that is completely mouse-proof. Eventually there will be evidence of mice in your shop. You may hear them in the walls, see their dropping on your workbench, or catch a glimpse of one scurrying away when you turn on the lights. When these events happen it’s time for extermination.
Extermination is trapping or poisoning the mice to get rid of them from your building. There are so many different types of mouse traps and new ones are being invented all the time. Rodent poisons have become more humane and less toxic to humans over the years too.
Mouse Traps
I’ve used many different types of mouse traps over the years. Some have worked very well, some so-so, and others not very good at all. One of the most effective ways to trap mice I found by accident years ago when I was building my first house.
It was winter time and the house was framed and weather-tight but not heated yet. I had a mouse problem. I would see them or their droppings all the time. One night when I left to go home I left a 5-gallon bucket that had a bit of water in the bottom on the garage floor next to the house wall which was just studs.
When I came back the next day there were at least a dozen dead mice in the bottom of the bucket. They must’ve jumped off the sub-floor of the house into the bucket looking for a source of water and they all drowned. There are many different varieties of this type of mouse trap now all over YouTube. We’ve tried a few different types like the spinning tube or a ramp and they do work very well.
I’ve also had good luck with the traditional Victor wooden mouse traps and some newer plastic versions that are somewhat similar. There’s a list of my recommended mouse traps on my resource page.
Rodent Poison
There are still rodenticides available that are dangerous to pets and people and some that claim that they are 100% safe. Personally I have only used poison when I had a bad mouse problem in the attic of my house and there was really no practical way to trap them.
If I were to buy a rodent poison now, I would consider RatX or MouseX. These products use corn gluten meal and sodium chloride to dehydrate the critters. These ingredients don’t affect other animals the same way and also don’t affect birds of prey that may have ingested a poisoned mouse.
As a last resort or if you are squeamish about killing mice, call a professional exterminator or animal control contractor. These services can be somewhat pricey, but the damage they cause can be even more costly.
